Kessler is leading Jazz rotation players in win shares/48 minutes (only Azebuike and Potter are higher), so he's already making a clear impact. Rookies often feel the need to prove themselves and end up trying to do too much to make an impression. Kessler is smart and doesn't do that, he plays the way he knows and it's helping the Jazz already. Even if this is all he is, he will be a solid rotation center for 10 years. But I'm irrationally optimistic and think he will expand his offensive game as he grows more accustomed to the NBA and gains confidence. I really wouldn't be surprised if he adds a 3 point shot at some point (even if it won't necessarily be pretty or great).